[Molecular and serological detection of enterotoxigenic staphylococcus aureus from traditionally dairy products]

ABSTRACT

Staphylococcus aureus is one of the most causes of food poisoning [FP] in dairy products. The main etiologic agent of FP is staphylococcal enterotoxins [SE]. There are different types of SE, but type A [SEA] and type B [SEB] are the most important types. Because traditional dairy products are still produced and sold without a permit from the Ministry of Health, this study was conducted to evaluate molecular and serological detection of enterotoxigenic Staphylococcus aureus SEA and SEB from traditionally dairy products. In the current study, 100 samples of dairy products, which were produced by traditional methods, were transported to the laboratory under sterile conditions and were assessed. Samples were cultured and identified by routine bacteriological methods. The isolated bacteria were evaluated by PCR tests for diagnosis of the gene encoding of SEA and SEB. Subsequently, the ability of above mentioned strains to produce enterotoxin were examined by Sac's culture method and were confirmed by SRID. Data were analyzed using chi-square test. The results indicated that 32% of dairy products were contaminated by Staphylococcus aureus [18% cream, 10% cheese, 4% milk]. The PCR results showed that 15.6% of Staphylococcus aureus isolates possessed the SEA gene, 9.3% had the SEB gene and 6.2% possessed both genes. The ability of enterotoxin production indicated that 80% of SEA and 33% of SEB genes were expressed. Enterotoxins SEA and SEB are heat stable; therefore heating has no effect on dairy products contaminated by entertoxins and gastritis may occur in a short period of time. As PCR is a rapid, sensitive, specific and inexpensive methods, we suggest that it can be replaced to traditionally assays for detecting SE